CDK SST

We had been using AWS and AWS SAM for our project for some time but still a lot of changes were made directly in the console.

When I started working in the team, there were some challenges I faced with the development process.

  • Since everything was on AWS, development and debug process was slow when using the console.
  • If writing code locally, there was no way to instantly debug it.
  • Unit testing this new application development model was not easy.
  • Deployments with Jenkins felt like an overkill since cloudformation does the job of finding change-sets and only deploying the differences.

After some discussion I decided to start fresh on a new infrastructure code, with some constraint in mind:

  • No manual action from AWS Console.
  • Developers during the development process should be able to provision their own infrastructure. (because its serverless model)
  • Javascript as the programming language.

Soon I lamded on AWS-CDK. And my initial impressions were "This is exacly what I was looking for!"

  • No more templating language (JSON/ YAML), pure native code. (JAVASCRIPT)
  • Unit testable infrastructure :star:
  • No manual console process.
  • CDK support multi-language
  • CDK hides complexity
  • CDK has a fast release cycle
  • CDK is based on cloud formation

HOW CDK support multi-languages

JSII is a framework developed by the technology that enables the CDK to deliver polyglot libraries from a single codebase!

Wait what is actually happening here?

  • AWS primarily uses Cloudformation which is written in JSON.
  • JSON is Javascript Object Notation, basically Javascript
  • AWS CDK is a wrapper around cloudformation in Javascript.
  • JSII is a Javascript framework that allows code in any language to naturally interact with JavaScript classes.

We write Write Python, Java, C# infrastructure code that gets converted into Javascript using jsii that CDK understands which again gets converted into Convert it into JSON that AWS Cloudformation understands.

This brings some problems with it!

Why typescript / javascript is better?

All components are written with typescript at first, so you are sure that they will work for you. With other languages, it works perfectly if you are using default CDK constructs but as soon as you are using 3rd party constructs it less certain that it will work.

I would recommend using Javascript for infrasturcture code even if some of the functionalities (lambdas) are in Python or Java.

What about Local Development Problem?

Yeah, the local development process problem is still a concern and there are some solutions out there addressing them:

  1. Serverless-Framework
  2. LocalStack
  3. SAM Local Invoke

They helped upto an extent but still did not felt right.

Welcome Serverless Stack Toolkit(SST)

SST is a tool built around AWS CDK and beautifully resolves local development problem by proxying lambda request using websocket connection. Everything else is runs on AWS.

Hey, I thought this article was about Infra-is-code!

YES it is. This article explains the journey from manual process to a place where Infrastruce is no more a template its core porgramming language code thats runs, deployes amd is tested like an application would. Its no more Infrastructure-As-Code its Infrastructure-Is-Code!

References